1. Technical Field
The present invention relates to a seat cushion airbag device, which suppress a forward movement of an object to be restrained such as an occupant seated on a seat portion of a vehicle seat such as a car seat, by inflating an airbag provided in the seat portion by an inflating fluid such as an inflating gas so as to cause a seat surface to bulge.
2. Background Art
When an impact is applied to the car from the front, e.g., by a frontal collision, a waist of an occupant restrained in a car seat by a seat belt device moves forward. This is a problematic phenomenon in a car. Consequently, various measures are being taken or proposed for suppression of the phenomenon.
As one of the various measures, there is an airbag device (a seat cushion airbag device) which is mountable to a vehicle seat including a seat portion. The seat portion includes a seat cushion supported from below by a support portion of a seat frame.
The airbag device includes: an airbag including an upper fabric portion and a lower fabric portion which are arranged to overlap with each other in an upper-lower direction and which are joined to each other to form a bag shape; and an inflator provided in a front portion of the airbag. The airbag device is intended to suppress the phenomenon by inflating the airbag by an inflating gas supplied from the inflator in response to the impact caused, e.g., by the frontal collision, such that a seat surface of the seat portion bulges, thereby suppressing the forward movement of the waist of the occupant seated on the seat portion.
For example, Patent Document 1 describes a vehicular seat built with a cushion airbag device. The cushion airbag includes a waist restraining portion that is arranged at a central portion of a cushion panel; and a gas introducing portion that connects the waist restraining portion to an inflator. The cushion airbag is inflated such that the waist restraining portion reaches a higher height than the gas introducing portion. Consequently, the waist of a seated occupant is pushed upward and restrained by the waist restraining portion.
The cushion airbag device further includes a connecting member provided in the waist restraining portion. The connecting member extends in a width direction of the car seat and connects two pieces of base cloth, thereby restricting the inflated shape of the waist restraining portion.
Patent Document 2 describes an airbag formed by joining an upper cloth and a lower cloth which are overlapped with each other in the upper-lower direction by joining means such as a seam. The airbag is partitioned into a plurality of inflation portions by the seam. The inflator is provided in the inflation portion located at the most front position of the inflation portions. Further, the adjacent inflation portions communicate with each other, whereby the inflating gas blown out from the inflator is supplied to all of the inflation portions through the communication portions.
According to the airbag, each of the inflation portions partitioned by the seam is inflated, and a necessary portion of the seat surface of the seat portion bulges. Consequently, the forward movement of the waist of the occupant can be suppressed.    Patent Document 1: JP 2012-016970 A (corresponding to US 2012/0007407 A1)    Patent Document 2: JP 2007-168599 A